Many treatments and procedures are carried out in industry utilizing high viscosity fluids to accomplish a number of purposes. For example, in the oil industry, high viscosity well treating fluids are utilized in treatments to increase the recovery of hydrocarbons from subterranean formations such as by creating fractures in the formations or acidizing the formations. High viscosity fluids are also commonly utilized in well completion procedures. For example, during the completion of a well, a high viscosity completion fluid having a high density is introduced into the well to maintain hydrostatic pressure on the formation which is higher than the pressure exerted by fluids contained in the formation thereby preventing the formation fluids from flowing into the wellbore.
In the past, such high viscosity treating fluids have commonly been prepared by using a number of dry additives which are mixed with water or other aqueous fluids at the job site. A number of disadvantages are inherent in such mixing procedures, particularly when large volumes of treating fluids are prepared. For example, special mixing equipment for mixing the dry additives with water is required and problems such as chemical dusting, uneven mixing, lumping of gels while mixing and extended preparation and mixing time are involved. In addition, the mixing and physical handling of large quantities of dry chemicals require a great deal of manpower, and where continuous mixing is required, the accurate and efficient handling of chemicals such as salts, gelling agents, gel breakers, fluid loss control additives, complexers and surfactants is extremely difficult.
Such high viscosity treating fluids have also been prepared from oil-based or water-based liquid gel concentrates, each of which have certain advantages and disadvantages. One disadvantage of water-based liquid gel concentrates has been that only relatively low polymer loading, typically around 1 lb/gal, has been achieved whereas oil-based liquid gel concentrates have achieved a polymer loading of typically about 3-4 lb/gal. However, some oil-based liquid gel concentrates carry restrictions with respect to usage in areas where environmental restrictions apply.
There is a need for water based liquid gel concentrates that can achieve higher polymer loadings than conventional water based liquid gel concentrates and are also non-toxic, non-flammable and more environmentally acceptable than oil-based liquid gel concentrates.